Bond event
Bond events are North Atlantic climate fluctuations occurring every ≈1,470 years throughout the Holocene. Eight such events have been identified. Bond events may be the interglacial relatives of the glacial Dansgaard-Oeschger events. The theory of 1,500-year climate cycles in the Holocene was postulated by Gerard C. Bond of the Lamont-Doherty Earth Observatory at Columbia University, mainly based on petrologic tracers of drift ice in the North Atlantic. The existence of climatic changes, possibly on a quasi-1,500 year cycle, is well established for the last glacial period from ice cores. Less well established is the continuation of these cycles into the holocene. Bond et al. (1997) argue for a climate cyclicity close to 1470 ± 500 years in the North Atlantic region. In their view, many if not most of the Dansgaard-Oeschger events of the last ice age, conform to a 1,500-year pattern, as do some climate events of later eras, like the Little Ice Age, the 8.2 kiloyear event, and the start of the Younger Dryas. Later proponents of this view include S. Fred Singer of the University of Virginia and Dennis Avery of the Hudson Institute, an American think-tank. They suggest that the current global warming is a Bond or Dansgaard-Oeschger event, and is therefore natural and unstoppable. The North Atlantic ice-rafting events happen to correlate with most weak events of the Asian monsoon over the past 9,000 years, as well as with most aridification events in the Middle East. Also, there is widespread evidence that a ≈1,500 yr climate oscillation caused changes in vegetation communities across all of North America. For reasons that are unclear, the only Holocene Bond event that has a clear temperature signal in the Greenland ice cores is the 8.2 kyr event. The hypothesis holds that the 1,500-year cycle displays nonlinear behavior and stochastic resonance; not every instance of the pattern is a significant climate event, though some rise to major prominence in environmental history. Causes and determining factors of the cycle are under study; researchers have focused attention on patterns of tides, variations in solar output, and "reorganizations of atmospheric circulation." List of Bond events Most Bond events do not have a clear climate signal; some correspond to periods of cooling, others are coincident with aridification in some regions. * ≈1,400 BP (Bond event 1) — roughly correlates with the Migration Period Pessimum (450–900 AD) * ≈2,800 BP (Bond event 2) — roughly correlates with the Iron Age Cold Epoch (900–300 BC) * ≈4,200 BP (Bond event 3) — correlates with the 4.2 kiloyear event * ≈5,900 BP (Bond event 4) — correlates with the 5.9 kiloyear event * ≈8,100 BP (Bond event 5) — correlates with the 8.2 kiloyear event * ≈9,400 BP (Bond event 6) — correlates with the Erdalen event of glacier activity in Norway, as well as with a cold event in China. * ≈10,300 BP (Bond event 7) — unnamed event * ≈11,100 BP (Bond event 8) — coincides with the transition from the Younger Dryas to the boreal References Category:Climate Category:Climatology Category:History of climate